package com.lagou.sqlSession;

import com.lagou.config.BoundSql;
import com.lagou.pojo.Configuration;
import com.lagou.pojo.MappedStatement;
import com.lagou.utils.GenericTokenParser;
import com.lagou.utils.ParameterMapping;
import com.lagou.utils.ParameterMappingTokenHandler;
import com.mchange.v2.lang.ObjectUtils;
import com.sun.org.apache.bcel.internal.generic.RET;

import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.sql.*;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class simpleExecutor implements Executor {

  @Override // user
  public <E> List<E> query(
      Configuration configuration, MappedStatement mappedStatement, Object... params)
      throws Exception {
    // 1. 注册驱动，获取连接
    Connection connection = configuration.getDataSource().getConnection();

    // 2. 获取sql语句 : select * from user where id = #{id} and username = #{username}
    // 转换sql语句： select * from user where id = ? and username = ? ，转换的过程中，还需要对#{}里面的值进行解析存储
    String sql = mappedStatement.getSql();
    BoundSql boundSql = getBoundSql(sql);

    // 3.获取预处理对象：preparedStatement
    PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSqlText());

    // 4. 设置参数
    // 获取到了参数的全路径
    String paramterType = mappedStatement.getParamterType();
    Class<?> paramtertypeClass = getClassType(paramterType);

    List<ParameterMapping> parameterMappingList = boundSql.getParameterMappingList();
    for (int i = 0; i < parameterMappingList.size(); i++) {
      ParameterMapping parameterMapping = parameterMappingList.get(i);
      String content = parameterMapping.getContent();

      // 反射
      Field declaredField = paramtertypeClass.getDeclaredField(content);
      // 暴力访问
      declaredField.setAccessible(true);
      Object o = declaredField.get(params[0]);

      preparedStatement.setObject(i + 1, o);
    }

    // 5. 执行sql
    ResultSet resultSet = preparedStatement.executeQuery();
    String resultType = mappedStatement.getResultType();
    Class<?> resultTypeClass = getClassType(resultType);

    ArrayList<Object> objects = new ArrayList<>();

    // 6. 封装返回结果集
    while (resultSet.next()) {
      Object o = resultTypeClass.newInstance();
      // 元数据
      ResultSetMetaData metaData = resultSet.getMetaData();
      for (int i = 1; i <= metaData.getColumnCount(); i++) {

        // 字段名
        String columnName = metaData.getColumnName(i);
        // 字段的值
        Object value = resultSet.getObject(columnName);

        // 使用反射或者内省，根据数据库表和实体的对应关系，完成封装
        PropertyDescriptor propertyDescriptor = new PropertyDescriptor(columnName, resultTypeClass);
        Method writeMethod = propertyDescriptor.getWriteMethod();
        writeMethod.invoke(o, value);
      }
      objects.add(o);
    }
    return (List<E>) objects;
  }

  public int deleteById(
      Configuration configuration, MappedStatement mappedStatement, Object... params)
      throws Exception {
      Connection connection = configuration.getDataSource().getConnection();
      BoundSql boundSql = this.getBoundSql(mappedStatement.getSql());
      PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSqlText());

      preparedStatement.setInt(1, (int) params[0]);
    int i = preparedStatement.executeUpdate();
    return i;
  }

  public int insert(Configuration configuration, MappedStatement mappedStatement, Object... params)
      throws Exception {

    Connection connection = configuration.getDataSource().getConnection();
    BoundSql boundSql = this.getBoundSql(mappedStatement.getSql());
      PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSqlText());

      Class<?> classType = this.getClassType(mappedStatement.getParamterType());
      List<Object> objects = new ArrayList<>();
      boundSql.getParameterMappingList().forEach(
              x-> {

                try {
                    String content = x.getContent();
                    Field declaredField = classType.getDeclaredField(content);
                    declaredField.setAccessible(true);
                    objects.add(declaredField.get(params[0]));

                } catch (Exception e) {
                    e.printStackTrace();
                }
            });
      for (int i=0;i<objects.size();i++){
          preparedStatement.setObject(i+1, objects.get(i));
      }
      int i = preparedStatement.executeUpdate();

      return i;
  }

    public int update(Configuration configuration, MappedStatement mappedStatement, Object... params)
            throws Exception {
        Connection connection = configuration.getDataSource().getConnection();
        BoundSql boundSql = this.getBoundSql(mappedStatement.getSql());
        PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSqlText());

        Class<?> classType = this.getClassType(mappedStatement.getParamterType());
        List<Object> objects = new ArrayList<>();
        boundSql.getParameterMappingList().forEach(
                x -> {

                    try {
                        String content = x.getContent();
                        Field declaredField = classType.getDeclaredField(content);
                        declaredField.setAccessible(true);
                        objects.add(declaredField.get(params[0]));
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                });
        for (int i=0;i<objects.size();i++){
            preparedStatement.setObject(i+1, objects.get(i));
        }
        int i = preparedStatement.executeUpdate();

        return i;
    }

//  private PreparedStatement getPreparedStatement(
//      Configuration configuration, MappedStatement mappedStatement) throws SQLException {
//    Connection connection = configuration.getDataSource().getConnection();
//    BoundSql boundSql = this.getBoundSql(mappedStatement.getSql());
//    return connection.prepareStatement(boundSql.getSqlText());
//  }

  private Class<?> getClassType(String paramterType) throws ClassNotFoundException {
    if (paramterType != null) {
      Class<?> aClass = Class.forName(paramterType);
      return aClass;
    }
    return null;
  }

  /**
   * 完成对#{}的解析工作：1.将#{}使用？进行代替，2.解析出#{}里面的值进行存储
   *
   * @param sql
   * @return
   */
  private BoundSql getBoundSql(String sql) {
    // 标记处理类：配置标记解析器来完成对占位符的解析处理工作
    ParameterMappingTokenHandler parameterMappingTokenHandler = new ParameterMappingTokenHandler();
    GenericTokenParser genericTokenParser =
        new GenericTokenParser("#{", "}", parameterMappingTokenHandler);
    // 解析出来的sql
    String parseSql = genericTokenParser.parse(sql);
    // #{}里面解析出来的参数名称
    List<ParameterMapping> parameterMappings = parameterMappingTokenHandler.getParameterMappings();

    BoundSql boundSql = new BoundSql(parseSql, parameterMappings);
    return boundSql;
  }
}
